Bump postgresql in /play-with-docker/example-voting-app/worker

Bumps [postgresql](https://github.com/pgjdbc/pgjdbc) from 9.4-1200-jdbc41 to 42.3.7.
- [Release notes](https://github.com/pgjdbc/pgjdbc/releases)
- [Changelog](https://github.com/pgjdbc/pgjdbc/blob/master/CHANGELOG.md)
- [Commits](https://github.com/pgjdbc/pgjdbc/commits/REL42.3.7)

---
updated-dependencies:
- dependency-name: org.postgresql:postgresql
  dependency-type: direct:production
...

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Author: dependabot[bot]

play-with-docker/example-voting-app/worker/pom.xml

@@ -26,7 +26,7 @@
     <dependency>
         <groupId>org.postgresql</groupId>
         <artifactId>postgresql</artifactId>
-        <version>9.4-1200-jdbc41</version>
+        <version>42.3.7</version>
     </dependency>
   </dependencies>